The concept of an alpha voltaic battery was proposed in 1954 as disclosed in W. G. Pfann and W. van Roosbroeck, Journal of Applied Physics, Volume 25, No. 11, pp. 1422-1434, November 1954, which is herein incorporated by reference. A radioactive substance that emits energetic alpha particles is coupled to a semiconductor p/n junction diode. As the alpha particles penetrate into the p/n junction, they decelerate and give up their energy as electron-hole pairs. These electron-hole pairs are collected by the p/n junction and converted into useful electricity, much like a solar cell.
The main reason alpha-voltaics and also beta-voltaics are not commercially successful is that the alpha or beta particles damage the semiconductor material as disclosed in G. C. Rybicki, C. V. Aburto, R. Uribe, Proceedings of the 25th IEEE Photovoltaic Specialists Conference, pp. 93-96, 1996, which is herein incorporated by reference. More specifically, the pn-junction in the alpha or beta voltaic device, which converts the alpha or beta particle radiation, respectively, from the radioactive isotope into electricity, rapidly degrades due to radiation damage rendering the alpha or beta voltaic device useless long before the radioisotope is depleted.